Correct, not just CA. We're CA-adjacent but our area schools have been doing this trip for some time. We have an organizer per school, but the high schools in our district all travel together. They travel in big ol' buses to CA (and the non-DLR activities), but they stay in the good neighbor hotels, so they walk to the parks.
I asked DD, and they didn't have to check in with their chaperones at the parks. I'm sure they buy the all-day hoppers+grad night b/c they think it's the best use of their time.
I must have read some old rules or something!!!!